
// Description : Array and textureless GLSL 4D simplex noise functions.
//      Author : Ian McEwan, Ashima Arts.
//  Maintainer : ijm
//     Lastmod : 20110813 (stegu)
//     License : Copyright (C) 2011 Ashima Arts. All rights reserved.
//               Distributed under the MIT License. See LICENSE file (copied below).

// Copyright (C) 2011 by Ashima Arts (Simplex noise)
// Copyright (C) 2011 by Stefan Gustavson (Classic noise)
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

// @BeginInterface

float snoise(vec4 v);

// @EndInterface

vec4 mod289(vec4 x) {
	return x - floor(x * (1.0 / 289.0)) * 289.0; }

float mod289(float x) {
	return x - floor(x * (1.0 / 289.0)) * 289.0; }

vec4 permute(vec4 x) {
	return mod289(((x*34.0)+1.0)*x);
}

float permute(float x) {
	return mod289(((x*34.0)+1.0)*x);
}

vec4 taylorInvSqrt(vec4 r)
{
	return 1.79284291400159 - 0.85373472095314 * r;
}

float taylorInvSqrt(float r)
{
	return 1.79284291400159 - 0.85373472095314 * r;
}

vec4 grad4(float j, vec4 ip)
{
	const vec4 ones = vec4(1.0, 1.0, 1.0, -1.0);
	vec4 p,s;

	p.xyz = floor( fract (vec3(j) * ip.xyz) * 7.0) * ip.z - 1.0;
	p.w = 1.5 - dot(abs(p.xyz), ones.xyz);
	s = vec4(lessThan(p, vec4(0.0)));
	p.xyz = p.xyz + (s.xyz*2.0 - 1.0) * s.www; 

	return p;
}

float snoise(vec4 v)
{
	const vec4  C = vec4( 0.138196601125011,  // (5 - sqrt(5))/20  G4
		0.276393202250021,  // 2 * G4
		0.414589803375032,  // 3 * G4
		-0.447213595499958); // -1 + 4 * G4

	// (sqrt(5) - 1)/4 = F4, used once below
#define F4 0.309016994374947451

	// First corner
	vec4 i  = floor(v + dot(v, vec4(F4)) );
	vec4 x0 = v -   i + dot(i, C.xxxx);

	// Other corners

	// Rank sorting originally contributed by Bill Licea-Kane, AMD (formerly ATI)
	vec4 i0;
	vec3 isX = step( x0.yzw, x0.xxx );
	vec3 isYZ = step( x0.zww, x0.yyz );
	//  i0.x = dot( isX, vec3( 1.0 ) );
	i0.x = isX.x + isX.y + isX.z;
	i0.yzw = 1.0 - isX;
	//  i0.y += dot( isYZ.xy, vec2( 1.0 ) );
	i0.y += isYZ.x + isYZ.y;
	i0.zw += 1.0 - isYZ.xy;
	i0.z += isYZ.z;
	i0.w += 1.0 - isYZ.z;

	// i0 now contains the unique values 0,1,2,3 in each channel
	vec4 i3 = clamp( i0, 0.0, 1.0 );
	vec4 i2 = clamp( i0-1.0, 0.0, 1.0 );
	vec4 i1 = clamp( i0-2.0, 0.0, 1.0 );

	//  x0 = x0 - 0.0 + 0.0 * C.xxxx
	//  x1 = x0 - i1  + 1.0 * C.xxxx
	//  x2 = x0 - i2  + 2.0 * C.xxxx
	//  x3 = x0 - i3  + 3.0 * C.xxxx
	//  x4 = x0 - 1.0 + 4.0 * C.xxxx
	vec4 x1 = x0 - i1 + C.xxxx;
	vec4 x2 = x0 - i2 + C.yyyy;
	vec4 x3 = x0 - i3 + C.zzzz;
	vec4 x4 = x0 + C.wwww;

	// Permutations
	i = mod289(i); 
	float j0 = permute( permute( permute( permute(i.w) + i.z) + i.y) + i.x);
	vec4 j1 = permute( permute( permute( permute (
		i.w + vec4(i1.w, i2.w, i3.w, 1.0 ))
		+ i.z + vec4(i1.z, i2.z, i3.z, 1.0 ))
		+ i.y + vec4(i1.y, i2.y, i3.y, 1.0 ))
		+ i.x + vec4(i1.x, i2.x, i3.x, 1.0 ));

	// Gradients: 7x7x6 points over a cube, mapped onto a 4-cross polytope
	// 7*7*6 = 294, which is close to the ring size 17*17 = 289.
	vec4 ip = vec4(1.0/294.0, 1.0/49.0, 1.0/7.0, 0.0) ;

	vec4 p0 = grad4(j0,   ip);
	vec4 p1 = grad4(j1.x, ip);
	vec4 p2 = grad4(j1.y, ip);
	vec4 p3 = grad4(j1.z, ip);
	vec4 p4 = grad4(j1.w, ip);

	// Normalise gradients
	vec4 norm = taylorInvSqrt(vec4(dot(p0,p0), dot(p1,p1), dot(p2, p2), dot(p3,p3)));
	p0 *= norm.x;
	p1 *= norm.y;
	p2 *= norm.z;
	p3 *= norm.w;
	p4 *= taylorInvSqrt(dot(p4,p4));

	// Mix contributions from the five corners
	vec3 m0 = max(0.6 - vec3(dot(x0,x0), dot(x1,x1), dot(x2,x2)), 0.0);
	vec2 m1 = max(0.6 - vec2(dot(x3,x3), dot(x4,x4)            ), 0.0);
	m0 = m0 * m0;
	m1 = m1 * m1;
	return 49.0 * ( dot(m0*m0, vec3( dot( p0, x0 ), dot( p1, x1 ), dot( p2, x2 )))
		+ dot(m1*m1, vec2( dot( p3, x3 ), dot( p4, x4 ) ) ) ) ;

}